1. Field of the Invention
This invention relates to golf clubs, and more particularly to a wood or iron having a shaft whose flexibility is predetermined during manufacture by tensioning a wire internal to the shaft and extending along its length.
2. Description of the Related Art
Application Ser. No. 09/553,594 is directed to a golf club having a hollow shaft whose flexibility can be altered by changing the tension on a wire coinciding with the shaft longitudinal axis. The wire is attached between a longitudinally movable assembly in the club handle and a fixed assembly at the shaft lower end. By rotating the handle, a golfer can determine through experimental trial which degree of flexibility best suits his or her particular full range of motion swing. The movable assembly, which includes outer and inner tension tuner members, a collar, a clamp and bifurcated collet, and outer and inner twist-prevention housings, is a complex mechanism built to close tolerances whose manufacturing cost is reflected in a relatively high sale price likely to discourage some potential buyers. To broaden market appeal there is a need for a simpler and therefore cheaper device which, while not offering a continuous range of shaft flexibility adjustment, allows a buyer to select a club whose shaft has been pretensioned at the factory to that flexibility best suited for that individual.
It is therefore an object of the present invention to provide a golf club incorporating a device which during manufacture allows the club shaft to be tuned to a preselected flexibility.
Another object of the invention is to provide a club whose shaft flexibility is preselectable during manufacture over a range of flexibilities.
A further object of the invention is to provide a club whose shaft imparts kinetic energy to the clubhead additional to that generated in the downswing of a conventional club.
Yet another object of the invention is to provide a device to tune shaft flexibility which is inexpensive to manufacture and readily adaptable to any club having a hollow shaft and clubhead.
Other objects of the invention will become evident when the following description is considered with the accompanying drawing figures. In the figures and description, numerals indicate the various features of the invention, like numerals referring to like features throughout both the drawings and description.
These and other objects are achieved by the present invention which in one aspect provides a golf club including a handle with a cavity having upper and lower portions, and a hollow shaft upper portion terminating in an upper end received within the cavity lower portion and symmetric about a longitudinal axis. The club further includes a hollow flexible shaft central portion, symmetric about the axis, attached at an upper end to the shaft upper portion and attached at a lower end to a hollow shaft lower portion, symmetric about the axis, which terminates in a lower end. The club further includes a cap member having an inner thread, and an outer surface received within the handle cavity upper portion. The club further includes a wire-end clamping member having a longitudinal bore and opposed planar upper and lower ends. The clamping member is radially compressible, and the cap member is superposed upon the compressed clamping member. The club further includes a tension support member having a cylindrical lower portion received within the shaft upper portion, a cylindrical upper portion having an outer thread, and an annular flange having opposed planar upper and lower surfaces. The flange is disposed between and attached to the support member upper and lower portions, and the flange lower surface contacts the upper end of the shaft upper portion. The cap member inner thread is in threaded combination with the outer thread of the upper portion. The club further includes a metallic wire, disposed along the axis and maintained at a constant tension, having opposed upper and lower wire-ends. The upper wire-end is maintained within the clamping member, and the lower wire-end is attached to the shaft portion lower end.
In another aspect the invention provides a golf club including a handle having a cap portion attached to a grip portion having a cylindrical interior surface and a scallop-contoured, downwardly tapering exterior surface. The cap portion and interior surface determine a cylindrical cavity having upper and lower portions. The club further includes a hollow downwardly tapering shaft upper portion terminating in an upper end received within the cavity lower portion and symmetric about a longitudinal axis, a hollow flexible, downwardly tapering shaft central portion, symmetric about the axis, which is attached at an upper end to the shaft upper portion and attached at a lower end to a hollow shaft lower portion, symmetric about the axis, having an inner wall and terminating in a lower end. The club further includes an upper wire-end retainer assembly including a cap member having a top portion, an inner thread, and a cylindrical outer surface received within the handle cavity upper portion. The retainer assembly further includes a radially compressible, hexagonal-shaped wire-end clamping member having opposed upper and, lower ends, an outer surface, and a constant cross-section longitudinal bore therethrough. The cap member is superposed upon the clamping member after it is compressed. The retainer assembly further includes a tension support member having a cylindrical lower portion received within the shaft upper portion, a cylindrical upper portion having an outer thread, and an annular flange having opposed upper and lower surfaces. The flange is disposed between and attached to the upper and lower portions, and the flange lower surface contacts the upper end of the shaft upper portion. The cap member inner thread is in threaded combination with the outer thread of the tension support member upper portion. The club further includes a lower wire-end retainer assembly including a cylindrical sleeve extending in a cylindrical flange. The sleeve and flange have therethrough a common bore, and a ring is received within the flange. The flange is attached to the inner wall of the shaft lower portion at its lower end. The club further includes a constant cross-section metallic wire having opposed upper and lower wire-ends and disposed along the longitudinal axis. The upper wire-end is closely received within the bore of the wire-end clamping member and is secured therein after the clamping member is radially compressed. The lower wire-end is attached to the ring of the lower wire-end retainer. The wire has a constant preselected tension.
A more complete understanding of the present invention and other objects, aspects and advantages thereof will be gained from a consideration of the following description of the preferred embodiments read in conjunction with the accompanying drawings provided herein.